Doctors are concerned West Australians are rejecting conventional treatment in favour of "faith healing" from a visiting Catholic priest.
There are claims New Zealand priest Father John Rea has cured ailments from cancer and deafness to chronic back pain and eczema in Perth.
Perth Catholic group Disciples of Jesus Covenant Community invited Father Rea to a series of Masses and "healing services" last month.
Catholic newspaper the Record has published accounts from local people who claimed they were healed, including a man who said his deafness disappeared after a service at St Mary's Cathedral.
A woman, identified only as Jenny L, said she sought Father Rea's help for her daughter's cancer on a previous trip to Perth and she had been free of the disease for a year.
Australian Medical Association WA president Richard Choong said belief was important but he was concerned someone might not seek treatment because they believed faith had healed them.
"Faith and belief is a really important part of recovery, and that's been demonstrated through history, but is that the only part? I don't think so," he said.
"I am very much concerned, when someone makes a claim that they can heal through faith, that those patients may not attend or seek medical advice or may halt treatment. That's unacceptable."
Father Rea rejected suggestions the apparent cures were a coincidence or attributable to the placebo effect. "The evidence indicates that these healings are real," he said.
"When they occur in great numbers, as they frequently do, they can hardly be attributed to luck.
"Nor can the placebo effect be invoked for the overnight healing of broken bones and similar healings.
"Cynics reject the possibility of divine healing because, if they admitted it, they would have to recognise the supernatural and, if honest, they would then have to change their lifestyle.
"Jesus Christ of Nazareth is the healer. He sometimes uses me as a kind of catalyst for healing but that is the extent of my involvement."
Father Rea said he did not know why some people were healed and not others.
Disciples of Jesus senior co-ordinator Reg Firth said Father Rea always encouraged people to maintain existing medical treatments, keep medical appointments and follow their doctor's advice.
"If God has healed, the practitioner will be the one to decide whether treatment is no longer required," he said.
"If people have yet to see a doctor, he would encourage them to do so."